Digital entertainment systems such as digital video recorders (DVRs), personal video recorders (PVRs), and digital video disc (DVD) players have received increased attention lately and have become popular. These digital entertainment systems are capable of reproducing video and/or audio content at a higher quality compared to conventional analog entertainment systems because the video and audio content are stored in digital format. The digital format of video content also facilitates implementation of program guides and manipulation of the video content by users.
Conventional DVRs typically receive video content either from a conventional video cable or through broadband connection, and encode and store the received video content in compressed digital formats such as MPEG-2 for future retrieval by a user. In this manner, users are able to view high quality video content at any desired time without deterioration of image quality as compared with analog recording of video content. One example of a conventional DVR is the ReplayTV® brand of DVRs.
Communications networks have a certain transmission rate in a given frequency band. For example, the IEEE 802.11a standard provides up to 54 Mbps transmission in the 5 GHz band. The IEEE 802.11b standard (also referred to as 802.11 High Rate or Wi-Fi) provides 11 Mbps transmission (with a fallback to 5.5 Mbps, 2 Mbps and 1 Mbps) in the 2.4 GHz band. The IEEE 802.11 g standard provides 20+Mbps in the 2.4 GHz band. The Bluetooth standard provides up to 720 Kbps data transfer in the 2.4 GHz band. As such, different video client devices in a video network may use different communications standards. Furthermore, the data transmission rate of the communication network between a video server and the video client devices may be affected by external conditions such as noise and the like. As such, these various communication networks can only handle video encoding standards and video encoding rates using a transmission rate lower than that of the video client device.
Furthermore, digital video encoding standards require a certain amount of bandwidth. For example, MPEG-1 uses a bandwidth ranging from 500 Kbps to 4 Mbps, averaging about 1.25 Mbps. MPEG-2 uses a bandwidth ranging from 4 to 16 Mbps. Bandwidths are typically dependent on source quality in addition to encoding technology. For example, MPEG-2 is generally more efficient than MPEG-1, but the official standards define their respective bit rates. That is, if desired, MPEG-1 could be run at a much higher bit rate than 4 Mb/sec. For the same bit rates, different encoding formats may have different source qualities. For example, at the same bit rate, MPEG-2 will generally have a higher source quality than MPEG-1.
In addition, video client devices may have limited processing speed depending upon the type of processors and memories they use. As such, the video client devices may be able to handle only certain types of video encoding standards and video encoding rates requiring a processing speed that is lower than the maximum processing speed supported by the video client devices. Also, the video client devices might also be limited by the particular codes that they support. For example, a video client device that does not include an MPEG-1 codec might not be able to playback MPEG-1 video content no matter how much processing speed the video client device supports.
Furthermore, certain types of video content may require higher a transmission rate in communications between the video server and the video client devices than other types of video content. For example, animation video contents would require higher data transmission rates for downloading because it requires a relatively high encoding rate in order to deliver good quality images. On the other hand, a concert recording would not require such high data transmission rates, because it does not require high encoding rates to deliver acceptable quality images of a concert scene.
Therefore, there exists a need for an improved method of transmitting video content between a video server and a video client device.